Air conditioning and heating effectiveness in a home or office environment can be greatly increased by using remotely controlled dampers to direct air flow into specific zones of the structure. These dampers typically use electromechanical devices to open or close moving panels or blades, or they consist of inflatable bladders that use air pressure to expand and vacuum pressure to contract. These dampers in turn control the air flow inside the air ducts to which they are attached. Dampers are installed in series with the air duct serving a particular zone of the structure. The dampers are typically linked to a central control panel by dedicated wiring or air hoses. The control panel is also connected to thermostats located in each zone that determine when heating, cooling or central ventilation is needed. Some thermostats have access to date and time information and, hence, can be programmed to request heating or cooling only when the zone is normally occupied. The central idea is to efficiently direct conditioned air or ventilation only to those areas where it is needed rather than attempting to sustain a certain temperature in the entire structure simultaneously.
One drawback in the use of the above-mentioned methods is the increased complexity and cost of wiring and piping needed in the attic of a structure to link the dampers and the thermostats with the control system. Each thermostat requires at least three wires, and sometimes as many as six wires to be connected to a central control system. Typically, five wires or an independent air hose for each damper is needed to link the dampers to the control system. The dampers generally require low voltage, alternating current or air pressure and vacuum pressure for operation. In the alternating current case, two wires are typically used to supply power and three wires are used to control the direction. For larger commercial applications, bundles of control wiring may range in size up to several inches in diameter to accommodate the numerous dampers and sensors located throughout these large structures. Both the installation and maintenance costs of these hardwired systems are of concern to builders, heating and air conditioning contractors, home owners and building managers. The complexity of a sophisticated system can make troubleshooting particularly difficult for the heating, ventilation and air conditioning (HVAC) technicians that provide installation or repair services. Advanced proportional air flow designs call for even more sophisticated control of these dampers so that they are positioned to meter the exact air flow desired for a particular zone. This method can add another level of wiring complexity to HVAC systems.